The upper cretaceousLacazina limestone in the Basco-Cantabrian and Iberian basins of northern Spain: Cold-water grain associations in warm-water environments

Summary The Upper Santonian to Lower CampanianLacazina Limestone consists of massive, often amalgamated beds of packstones and grainstones which were deposited in a shallow marine environment. The most abundant skeletal components are miliolid foraminifera, echinoderm, bivalve and bryozoan fragments, peloids and sparse red algae. Small, solitary corals only occur sporadically. Hermatypic corals, sponges and green algae are missing. The series which reaches thicknesses between 60 m and 160 m, was sampled at intervals of 0.5 m at five localities. The petrographic features throughout the series are mainly a product of changing depositional energy. The limestones are well cemented. Diagenesis is characterized by a transition from marine phreatic to burial cementation. Syntaxial and blocky calcite cements predominate over early acicular to bladed and microgranular cements. The faunal association within theLacazina Limestone exhibits features typical for temperate water i.e.foramol carbonates. On the other hand, oxygen (δ¹⁸O =-1.7 to −6.3 ‰ PDB) and carbon (δ¹³C to 3.0‰ PDB) isotope values of diagentically unaltered bivalve shells indicate warm surface waters corresponding better to the palaeogeographical situation of theLacazina Limestone. Nutrient-surplus is proposed as a limiting factor preventing the development of reefs and finally ofchlorozoan sediments. In the sense of sequence stratigraphy, theLacazina Limestone is interpreted to contain transgressive and highstand systems tracts. This interpretation fits well into theHaq-Vail-curve. The series shows no visible high-frequency cyclicity in the field. Several cycles were found by means of principle component analysis and spectral analysis. Their relationships to the Milankovitch spectrum are discussed. The ammonite fauna of the unit and of preceding sediments (late Coniacian to early Campanian) is described and some inoceramids are figured. They permit—for the first time—the exact dating of theLacazina Limestone in the Basco-Cantabrian Basin (BCB) and throw light on a prominent faunal change at the Coniacian/Santonian boundary. The Cenomanian to Coniacian ammonite faunas which were dominated by endemic Tethyan pseudoceratitic faunas are replaced by cosmopolitan species dominated by Madagascan elements. This drastic change permits speculations about the installation of a new oceanic current system in the Santonian.     

Dynamic process conditions in bioprocess development

In this review, we summarise recent studies that purposefully employed dynamic conditions, such as shifts, pulses, ramps and oscillations, for fast physiological strain characterisation and bioprocess development. We show the broad applicability of dynamic conditions and the various objectives that can thereby be investigated in a short time. Dynamic processes reveal information about the analysed system faster than traditional strategies, like continuous cultivations, as process parameters can directly be linked to platform and product parameters. Furthermore, we demonstrate that dynamic operations can result in increased productivity and high product quality, making this strategy a valuable tool for bioprocess development. With this review, we would like to encourage bioprocess engineers to an increased use of dynamic conditions in bioprocess development.     

Paleoenvironmental model for Eocene foraminiferal limestones of the Adriatic carbonate platform (Istrian Peninsula)

The foraminiferal limestones from the Middle Eocene Central Istrian region illustrate progressive deepening of depositional gradients. Shifting of Lower Cuisian to Upper Lutetian microfacies can be described in terms of a ramp model. The Orthophragminae-bearing parts of the foraminiferal limestones are interpreted in terms of larger foraminiferal faunal associations, planktonic foraminiferal relative abundance, limitations of algal endosymbionts, foraminiferal lamellar thickness and flattening of test shapes. Microfacies I contains the most diverse larger foraminiferal association with a predominance of large, thick nummulitids, assilinids, and asterocyclinids. Microfacies II is characterized by a gradual increase of Orthophragminae diversity and abundance. Nummulitids, equally abundant, are dominated by lenticular and subspherical specimens. The reduction in number of nummulitid specimens with characteristic biconical radiate morphologies, and relative abundance of flattened orthophragminids, characterizes Microfacies III. Scattered biodestructed orthophragminid tests and planktonic foraminifera constitute Microfacies IV, indicating the end of a long-lasting, shallow-marine Adriatic Carbonate Platform regime.     

Muscle work is biased toward energy generation over dissipation in non-level running

This study tested the hypothesis that skeletal muscles generate more mechanical energy in gait tasks that raise the center of mass compared to the mechanical energy they dissipate in gait tasks that lower the center of mass despite equivalent changes in total mechanical energy. Thirteen adults ran on a 10° decline and incline surface at a constant average velocity. Three-dimensional (3D) joint powers were calculated from ground force and 3D kinematic data using inverse dynamics. Joint work was calculated from the power curves and assumed to be due to skeletal muscle–tendon actuators. External work was calculated from the kinematics of the pelvis through the gait cycle. Incline vs. decline running was characterized with smaller ground forces that operated over longer lever arms causing larger joint torques and work from these torques. Total lower extremity joint work was 28% greater in incline vs. decline running (1.32 vs. −1.03 J/kg m, p<0.001). Total lower extremity joint work comprised 86% and 71% of the total external work in incline (1.53 J/kg m) and decline running (−1.45 J/kg m), which themselves were not significantly different (p<0.180). We conjectured that the larger ground forces in decline vs. incline running caused larger accelerations of all body tissues and initiated a greater energy-dissipating response in these tissues compared to their response in incline running. The runners actively lowered themselves less during decline stance and descended farther as projectiles than they lifted themselves during incline stance and ascended as projectiles. These data indicated that despite larger ground forces in decline running, the reduced displacement during downhill stance phases limited the work done by muscle contraction in decline compared to incline running.     

Autochthonous outer ramp sedimentation: The Alamogordo Member of the Lake Valley Formation,New Mexico

Summary Paleozoic carbonate ramp sedimentation has generally been described in terms of downlapping clinoforms composed of allochthonous sediment derived from shallower environments. However, during transgressive episodes when carbonate sediment production is low and down slope sediment transport by gravity becomes inactive, autochthonous carbonate sediment accumulates in vertical stacks of essentially in situ sediment. Autochthonous outer ramp deposition is probably a part of many Paleozoic ramp strata, but has heretofore not been recognized because of the general absence of adequate exposures. Evidence of autochthonous, in situ deposition and preservation of sediments in a starved setting is well displayed in the Alamogordo Member of the Lake Valley Formation in south central New Mexico. This evidence includes: 1) beds and bed sets that are individually continuous and traceable along ramp slope for 32 km, 2) down-ramp sequential distributions of depth-sensitive organisms and assemblages but patchy distribution of rock types, 3) lack of sedimentary structures indicative of transport, 4) well preserved, unabraded fossils, 5) the common occurrence of fossils in life position, 6) beds traceable into and through mounds 7) bed thickness trends ascribed to biotic productivity, and 8) geopetal structures in original position. Integrated paleontologic, sedimentologic, and stratigraphic data provide information about depositional processes and setting. The depositional slope was approximately 0.5^o based on the distribution of fossil algae; this is comparable to dips reported for other Mississippian homoclinal ramps. An oxygen minimum zone may have impinged on the ramp during a major flooding event. Shifts in biotic gradients from bed to bed reveal transgressive-regressive patterns that would not be resolvable without detailed paleontological evidence. The Alamogordo Member formed as a result of transgressive and early highstand starved carbonate sedimentation along a narrow, homoclinal outer ramp. The surface of maximum flooding and the boundary between the TST and HST are within the Alamogordo Member.     

Electrophysiology of the marine diatom Coscinodiscus wailesii IV: types of non-linear current-voltage-time relationships recorded with single saw-tooth voltage-clamp experiments

Electrophysiological states of the marine diatom Coscinodiscus wailesii are known to change spontaneously in the temporal range of seconds. In order to assess the genuine current-voltage-time relationships of individual states in less than a second, voltage-clamp experiments have been carried out using single sweeps of saw-tooth shaped command voltages. This method is introduced with model calculations. Plotting the results in current-voltage coordinates provides convenient access to several electrophysiological entities, such as absence of drift (smoothly closed IV loops), membrane capacitance (by I jump at sign reversal of dV/dt), and ohmic conductances (in linear regions of the current-voltage relationship), as well as equilibrium voltage (internal intersection of capacitance-corrected, 8-shaped tracings) and coarse gating kinetics (rise or fall of capacitance-corrected I at sign reversal of dV/dt) of a voltage-sensitive ion conductance. From electrophysiological measurements with double-barreled glass-microelectrodes on C. wailesii, several distinct types of current-voltage loops are presented. Most of the data, including recordings from electrical excitation, can be interpreted as temporal relaxations of voltage-sensitive conductances for K⁺ and Cl⁻. A more detailed analysis of the effect of tetraethylammonium (TEA⁺) shows that 10 and 20 mM TEA⁺ inhibit the K⁺ conductance in C. wailesii only by up to about 20% but predominantly via a K⁺ outward rectifier. Received: 23 December 1998 / Revised version: 1 June 1999 / Accepted: 1 June 1999     

EMG power spectra of elbow extensors during ramp and step isometric contractions

The goal of the present study was to compare electromyogram (EMG) power spectra obtained from step (constant force level) and ramp (progressive increase in the force level) isometric contractions. Data windows of different durations were also analysed for the step contractions, in order to evaluate the stability of EMG power spectrum statistics. Fourteen normal subjects performed (1) five ramp elbow extensions ranging from 0 to 100% of the maximum voluntary contraction (MVC) and (2) three stepwise elbow extensions maintained at five different levels of MVC. Spectral analysis of surface EMG signals obtained from triceps brachii and anconeus was performed. The mean power frequency (MPF) and the median frequency (MF) of each power spectrum were obtained from 256-ms windows taken at 10, 20, 40, 60 and 80% MVC for each type of contraction and in addition on 512-, 1024- and 2048-ms windows for the step contractions. No significant differences (P greater than 0.05) were found in the values of both spectral statistics between the different window lengths. Even though no significant differences (P greater than 0.05) were found between the ramp and the step contractions, significant interactions (P less than 0.05) between these two types of contraction and the force level were found for both the MPF and the MF data. These interactions point out the existence of different behaviours for both the MPF and the MF across force levels between the two types of contraction.     

Activation of Calcitonin Receptor and Calcitonin Receptor-like Receptor by Membrane-anchored Ligands

G protein-coupled receptors (GPCRs) are the most important pharmaceutical targets, and more than 40% of drugs in use today modulate GPCR signaling. A major hurdle in the development of therapies targeting GPCRs is the drug candidate''s nonselective actions in multiple tissues. The ability to spatially control GPCR signaling would provide a venue for developing therapies that require targeted GPCR signaling. Here, we show that the fusion of a RAMP1 co-receptor with the calcitonin gene-related peptide (CGRP), or calcitonin, transforms the RAMP1 from a co-receptor to bona fide membrane-anchored ligands (CGRP-RAMP1 and CAL-RAMP1). The CAL-RAMP1 selectively activates the calcitonin receptor (CR), whereas, the CGRP-RAMP1 activates both the calcitonin receptor-like receptor (CLR) and CR. Unlike a free peptide, which moves freely in the extracellular space and differentiates targets based on molecular affinity, the anchored CGRP-RAMP1 and CAL-RAMP1 ligands confine their activities to individual cells. In addition, our study showed that a CGRP8–37-RAMP1 chimera, but not RAMP1, functions as an antagonist for CGRP-RAMP1-mediated signaling, suggesting that the activation of CLR by CGRP-RAMP1 shares similar molecular mechanisms with the CGRP-mediated activation of CLR/RAMP1 receptor complexes. Taken together, our finding thus provides a novel class of ligands that activate CR and CLR exclusively in an autocrine manner and a proof-of-concept demonstration for future development of targeted therapies aimed at these receptors in specific cell populations.     

Variations in the off-axis refractive state in the eye of the Vietnamese leaf turtle (<Emphasis Type="Italic">Geoemyda spengleri</Emphasis>)

Lower-field myopia has been described for various vertebrates as an adaptation that permits the animal to keep the ground in focus during foraging, and, at the same time, to look out for distant objects, such as predators, in the upper visual field. Off-axis measurements with infrared photoretinoscopy in the eye of Geoemyda spengleri revealed a constant refractive state in the horizontal plane of the visual field but variable refraction in the vertical plane. In the three turtles investigated, the refractions increased continuously from the ventral to the dorsal visual field over a range of 35, 40 and 56 D, respectively. While this finding confirms the presence of an adaptive change of the refractive state equivalent to lower field myopia, subsequent measurements with a rotated retinoscope showed that at least part of the variation in the ventral field was attributed to astigmatism. The reason for this astigmatism is unknown. Anatomical investigation of the retina revealed that the constant refractive values in the horizontal plane corresponded to a stripe of increased ganglion cell density. A maximum density of 4,200 ganglion cells mm^–2 was counted in the centre of this visual streak.     

Active recovery has a positive and acute effect on recovery from fatigue induced by repeated maximal voluntary contractions of the plantar flexors

This study investigated the acute effect of active recovery (AR) following fatigue induced by 80 three-second maximal voluntary isometric plantar flexion contractions (MVICs) in 12 young men. AR consisted of a total of 180 voluntary isometric ramp contractions of the plantar flexors (0.75-s contraction/relaxation) targeting 10% of MVIC torque. MVIC torque, voluntary activation and root mean square values of electromyographic signals for the triceps surae normalized by each peak-to-peak amplitude of compound motor action potential were determined before, and immediately, 10, 20 and 30 min after the fatiguing task. Evoked torques were similarly assessed except for immediately after it. The AR and passive recovery were randomly performed on two days by each participant between 5 min and 10 min after the fatiguing task. For all the parameters other than MVIC torque, there was no significant difference between the conditions at any time point. MVIC torque decreased significantly immediately after the fatiguing task regardless of condition (P < 0.05), and the corresponding decrease in MVIC torque recovered 30 min after the fatiguing task only in AR (P < 0.05). These results suggest an acute positive effect of AR on recovery of neuromuscular function and/or contractile properties after fatigue.